What important background information is established in the first scene?

Antonio, a merchant, is in a melancholic (sad) state of mind and unable to find a reason for his depression. His friends Salerio and Solanio attempt to cheer him up by telling him that he is only worried about his ships returning safely to port. Antonio, however, denies that he is worried about his ships and remains depressed. Bassanio comes along informs Antonio that he has been loose with his money and that he currently has accumulated substantial debts. Bassanio reveals that he has come up with a plan to pay off his obligations by marrying Portia, a wealthy heiress in Belmont. However, in order to woo Portia, Bassanio needs to borrow enough money so that he can act like a true nobleman. Antonio tells him that all his money is invested in ships at sea, but offers to borrow money for him.